In their eagerness to serve, the sheriffs on Comedy Central's Reno 911! will even shoot a dog to save a man from having to put his sick pet to sleep. Just one problem: It's not his dog. He's a dog-hating neighbor.

Canine killing is not the stuff of traditional sitcoms, but it offers a hint of how different the critically praised, second-year Comedy Central series is. Dialogue is improvised by the cast, which includes producers Robert Ben Garant, Kerri Kenney-Silver and Thomas Lennon; laughs often come from nervous tension, not punch lines.

The offbeat style of Reno (tonight, 10:30 ET/PT), a comic spin on Cops, has made it the channel's No. 3 series, behind South Park and Chappelle's Show. (The first-season DVD is out this week.)

Reno's producers don't think it would have survived on network TV. "We couldn't get away with this anywhere else," Garant says.

Garant, Kenney-Silver and Lennon, who joined forces at New York University, envisioned Reno as a sketch show focusing on the interaction between officers and criminals. "As we filmed the pilot, it surprised us how much we actually cared about the characters. The show is not about the perps at all. It's about the cops," Garant says.

That's not to say Reno doesn't have some entertaining criminals, such as a serial-killing suspect who's also the love interest of Officer Trudy Wiegel (Kenney-Silver). Season 2 also features an influx of guests, including Traci Bingham, Wayne Brady, Dick Gregory, Lorenzo Lamas and Kenny Rogers.

And scenes are taped at a real law enforcement agency: the Carson, Calif., Sheriff's Department. "They were a little bit nervous at first, but now they see we're just playing these characters. We're not doing an anti-cop show at all," Garant says. "They pitch us jokes."